A systematic review of 37 randomized controlled trials showed promising evidence for the ability of yoga to improve cardiovascular and metabolic health, but found no significant difference in the effectiveness of yoga versus aerobic exercise.

Yoga showed significant improvement in body mass index, systolic blood pressure, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol; and significant changes in body weight, diastolic blood pressure, total cholesterol, triglycerides, and heart rate. ‘

“Despite the growing evidence on the health implications of yoga, the physiological mechanisms behind the observed clinical effects of yoga on cardiovascular risk remain unclear,” the researchers say, adding that “there’s a need for larger randomized controlled studies that meet explicit, high quality methodological standards to ascertain the effects of yoga” in improving modifiable risk factors of  cardiovascular disease and metabolic syndrome.

Cardiovascular disease (CVD) and metabolic syndrome are major public health problems in the USA and worldwide. Metabolic syndrome is defined as having at least three metabolic risk factors — increased blood pressure, high blood sugar level, excess body fat, and abnormal cholesterol levels — and greatly increases chance of future cardiovascular problems. CVD and metabolic syndrome share many of the same modifiable risk factors, such as physical inactivity, the fourth leading risk factor of global mortality, the researchers note.

The study, by researchers at Erasmus MC, Harvard Medical School, and Harvard School of Public Health, was published (open-access) in the European Journal of Preventive Cardiology.

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Abstract of The effectiveness of yoga in modifying risk factors for cardiovascular disease and metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

Background Yoga, a popular mind-body practice, may produce changes in cardiovascular disease (CVD) and metabolic syndrome risk factors.

Design This was a systematic review and random-effects meta-analysis of randomized controlled trials (RCTs).

Methods Electronic searches of MEDLINE, EMBASE, CINAHL, PsycINFO, and The Cochrane Central Register of Controlled Trials were performed for systematic reviews and RCTs through December 2013. Studies were included if they were English, peer-reviewed, focused on asana-based yoga in adults, and reported relevant outcomes. Two reviewers independently selected articles and assessed quality using Cochrane’s Risk of Bias tool.

Results Out of 1404 records, 37 RCTs were included in the systematic review and 32 in the meta-analysis. Compared to non-exercise controls, yoga showed significant improvement for body mass index (−0.77 kg/m² (95% confidence interval −1.09 to −0.44)), systolic blood pressure (−5.21 mmHg (−8.01 to −2.42)), low-density lipoprotein cholesterol (−12.14 mg/dl (−21.80 to −2.48)), and high-density lipoprotein cholesterol (3.20 mg/dl (1.86 to 4.54)). Significant changes were seen in body weight (−2.32 kg (−4.33 to −0.37)), diastolic blood pressure (−4.98 mmHg (−7.17 to −2.80)), total cholesterol (−18.48 mg/dl (−29.16 to −7.80)), triglycerides (−25.89 mg/dl (−36.19 to −15.60), and heart rate (−5.27 beats/min (−9.55 to −1.00)), but not fasting blood glucose (−5.91 mg/dl (−16.32 to 4.50)) nor glycosylated hemoglobin (−0.06% Hb (−0.24 to 0.11)). No significant difference was found between yoga and exercise. One study found an impact on smoking abstinence.

Conclusions There is promising evidence of yoga on improving cardio-metabolic health. Findings are limited by small trial sample sizes, heterogeneity, and moderate quality of RCTs.